A superior electrode for high-performance supercapacitors has been designed by growing homogeneous NiO nanoparticles on conductive Ni foam substrate through a facile two-step method. The preparation strategy involves the electrodeposition of nickel hydroxide precursor on Ni foam and subsequent low-temperature annealing process. These NiO nanoparticles are interconnected with each other, forming a loose network with a highly open and porous structure. This unique 3D NiO-Ni foam electrode manifests the electrolyte penetration and ion migration as well as large electroactive surface area. As a result, outstanding pseudocapacitive performance is achieved with a high specific capacitance (2558 Fg(-1) at 2 A g(-1) in a potential window of 0.5 V) and excellent rate capability (70% capacity retention at 40A g(-1)), which shows great potential in the development of high-performance energy-storage systems. (C) 2013 Elsevier Ltd. All rights reserved.